Acute idiopathic polyneuritis. A clinical and electrophsiological follow-up study.

Fifty patients with acute idiopathic polyneuritis have been studied clinically and electromyographically, and sural nerve biopsy was performed on 8 patients. Motor and sensory conduction studies were within the normal range in 7 patients (14%), and there was pronounced slowing of motor conduction in 25 patients (50%). There was no apparent correlation between the degree of conduction, and the clinical disability of the patient or the duration of the acute illness. Eighteen patients were re-examined at intervals up to 5 1/2 years after the onset of their illness. Eight patients (44%) were clinically normal at follow-up examination and 4 patients (22%) had a significant disability. There was no relationship between the clinical disability at follow-up examination and the results of initial or final nerve conduction studies. Electromyographic evidence of denervation, however, may indicate that complete clinical recovery will not occur. Segmental demyelination was the primary pathological change found in sural nerve biopsies and there was a significant reduction in the density of myelinated fibres in 2 nerves. It is suggested that a subacute onset of the illness,electromyographic evidence of denervation or gross slowing of conduction, and significant reduction of numbers of myelinated fibres or onion-bulb formation on sural nerve biopsy are factors which may indicate a prolonged course of the illness or incomplete recovery.